app/vmalert/datasource/graphite: allow overriding "from" parameter for datasource queries (#4687)

* app/vmalert/datasource/graphite: allow overriding "from" parameter for datasource queries

Fixes construction of URL parameters for graphite render to allow overriding "from" parameter.

See: https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4685
Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

* app/vmalert/datasource/graphite: update flow for building URL parameters

Makes flow of building URL parameters same as Prometheus datasource has:
1) Setting all default values
2) Merging those values with provided `extraParams`

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>

* Update docs/CHANGELOG.md

Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>

---------

Signed-off-by: Zakhar Bessarab <z.bessarab@victoriametrics.com>
Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>

app/vmalert/datasource/vm_graphite_api.go

@@ -54,6 +54,16 @@ func (s *VMStorage) setGraphiteReqParams(r *http.Request, query string, timestam
 	}
 	r.URL.Path += graphitePath
 	q := r.URL.Query()
+	from := "-5min"
+	if s.lookBack > 0 {
+		lookBack := timestamp.Add(-s.lookBack)
+		from = strconv.FormatInt(lookBack.Unix(), 10)
+	}
+	q.Set("from", from)
+	q.Set("format", "json")
+	q.Set("target", query)
+	q.Set("until", "now")
+
 	for k, vs := range s.extraParams {
 		if q.Has(k) { // extraParams are prior to params in URL
 			q.Del(k)
@@ -62,14 +72,6 @@ func (s *VMStorage) setGraphiteReqParams(r *http.Request, query string, timestam
 			q.Add(k, v)
 		}
 	}
-	q.Set("format", "json")
+
-	q.Set("target", query)
-	from := "-5min"
-	if s.lookBack > 0 {
-		lookBack := timestamp.Add(-s.lookBack)
-		from = strconv.FormatInt(lookBack.Unix(), 10)
-	}
-	q.Set("from", from)
-	q.Set("until", "now")
 	r.URL.RawQuery = q.Encode()
 }

app/vmalert/datasource/vm_test.go

@@ -611,6 +611,20 @@ func TestRequestParams(t *testing.T) {
 				checkEqualString(t, exp, r.URL.RawQuery)
 			},
 		},
+		{
+			"graphite extra params allows to override from",
+			false,
+			&VMStorage{
+				dataSourceType: datasourceGraphite,
+				extraParams: url.Values{
+					"from": {"-10m"},
+				},
+			},
+			func(t *testing.T, r *http.Request) {
+				exp := fmt.Sprintf("format=json&from=-10m&target=%s&until=now", query)
+				checkEqualString(t, exp, r.URL.RawQuery)
+			},
+		},
 	}
 
 	for _, tc := range testCases {

docs/CHANGELOG.md

@@ -47,6 +47,7 @@ The following `tip` changes can be tested by building VictoriaMetrics components
 * FEATUTE: [vmalert](https://docs.victoriametrics.com/vmalert.html): allow disabling of `step` param attached to [instant queries](https://docs.victoriametrics.com/keyConcepts.html#instant-query). This might be useful for using vmalert with datasources that to not support this param, unlike VictoriaMetrics. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4573) for details.
 * FEATUTE: [vmalert](https://docs.victoriametrics.com/vmalert.html): support option for "blackholing" alerting notifications if `-notifier.blackhole` cmd-line flag is set. Enable this flag if you want vmalert to evaluate alerting rules without sending any notifications to external receivers (eg. alertmanager). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4122) for details. Thanks to @venkatbvc for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4639).
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert.html): add unit test for alerting and recording rules, see more [details](https://docs.victoriametrics.com/vmalert.html#unit-testing-for-rules) here. Thanks to @Haleygo for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/4596).
+* FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert.html): allow overriding default GET params for rules  with `graphite` datasource type, in the same way as it happens for `prometheus` type. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4685). 
 * FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth.html): expose `vmauth_user_request_duration_seconds` and `vmauth_unauthorized_user_request_duration_seconds` summary metrics for measuring requests latency per user.
 * FEATURE: [vmbackup](https://docs.victoriametrics.com/vmbackup.html): show backup progress percentage in log during backup uploading. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4460).
 * FEATURE: [vmrestore](https://docs.victoriametrics.com/vmrestore.html): show restoring progress percentage in log during backup downloading. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4460).